What Happens If We Can't Leave Earth?
This episode is brought to you by Raycon. So much of our discussions of the future here on this show and elsewhere assume a grand destiny out among the stars. But what if we’re wrong and that glorious future on the horizon is merely a mirage? A few months back I asked our audience over on our reddit group, r/IsaacArthur, for some episode ideas, and there were so many good ones that I decided to take 5 of the most upvoted and put them on our Youtube Community page for a poll, and the clear winner was today’s topic, what happens if we can’t leave Earth? One of the things I tend to be best known for is talking about how to get us off Earth and to new planets so I was a bit surprised by that being a topic folks wanted me to discuss. Of course another thing I tend to be well-known for is being pretty upbeat about humanity’s future and as we’ll see today, even if we can’t get off Earth, that doesn’t make for a bleak future at all. We don’t really see a distant future on Earth discussed very much, scifi in a galactic setting rarely does much here in favor of strange new worlds, and Earth tends to either be the distant capital of some stellar empire or a distant memory of a world long since destroyed. When we do see Earth as the centerpiece of such stories, it is usually the Dying Earth saga, inevitably dystopian stories set in an exhausted planet which is either spurned by its distant colonies or unaided because they have the same exhaustion.
Dead mined planets around dying stars, and Earth a fading ember waiting to die by fire or ice. Indeed so much of classic science fiction drums that point in, to encourage us to want to reach out to claim those stars. One of my favorites quotes on the topic is from Commander Sinclair of the 90s scifi show Babylon 5, in the episode “Infection” when asked by a reporter from Earth about the great expense of keeping his space station running and the cost and risk of other space endeavors. She asks,” I have to ask you the same question
people back home are asking about space these days. Is it worth it? Should we just pull back? Forget the whole thing as a bad idea, and take care of our own problems at home?” And Sinclair replies, “No. We have to stay here. And there's a simple reason why. Ask ten different scientists about the environment, population control, genetics, and you'll get ten different answers. But there's one thing every scientist on the planet agrees on. Whether it happens in a hundred years or a thousand years or a million years, eventually our Sun will grow cold and go out. When that happens, it won't just take us. It'll take Marilyn Monroe, and Lao-Tzu, and Einstein, and Morobuto, and Buddy Holly, and Aristophanes, and all of this…all of this…was for nothing. Unless we go to the stars.”
I love that line, it’s very poetic. I think it summarizes how a lot of us feel about space. But in a couple of months we will ‘celebrate’ the 50th anniversary of the last time humanity walked on the Moon, and I don’t think even space pessimists of that time thought we would be over half a century going back and not have done a manned mission to Mars by now. I firmly believe we need no new science and only a handful of technological improvements to make space a reality, that vast improvements to both can only help but aren’t needed, and we discussed the very low-tech approaches in our episodes Crawlonizing the Galaxy and Low-Tech Kardashev Civilizations. Nonetheless there’s no guarantee those things will happen. That we will just find a way to make space colonization viable, and we can show the
practical engineering and raw numbers for travel but there’s a big difference between inventing a ship sail and actually creating large-scale intercontinental oceanic trade. There are so many tiny little problems with sailing a boat across an ocean that took centuries to figure out and many of those major problems weren’t visible until we began early journeys. Space travel is hard, and it's likely there are critical problems with doing it we don’t even know of yet.
So I remain confident it will happen but we can’t casually ignore that we might just be wrong about this. Indeed until those Apollo Missions were done, we didn’t even have the term Fermi Paradox, and Fermi himself was just of the opinion that alien races were common enough but that interstellar space travel wasn’t and that species don’t long survive technology, a bit of pessimism that is understandable from one of the inventors of nuclear weapons who got to see the arsenals and tensions grow in the Cold War, but not live to see the Space Race. And it wasn’t really a perspective that was new, scifi was playing around with interstellar colonization throughout the 20th century and before then nobody really contemplated space travel and settlement in a serious way, even though we had an increasingly strong knowledge that the Universe was huge and ancient and that our sun was just another star. Indeed pre-20th
century with Radio Waves and Relativity, ever since Newton’s laws of gravity, we assumed the universe was infinite in age and size. So when it was discussed everybody assumed that life was either the unique creation of the divine or that life probably was all over the place but that travel was impossible and of course travel was the only way to communicate. There was no phone or radio after all, communication by default was done by walking or riding or sailing to either talk to someone in person or hand them a letter. So the idea that our future was ‘space or bust’ is definitely a new one, and while just about every religion and culture had some built in doomsday event they expected, it was usually nebulous and set to arrive whenever and while it often involved the heavens it was in a different mental context. The end was a thing to be welcomed or dreaded or maybe both, but folks didn’t really think in billion year timelines back then anymore than we do now. With a few notable exceptions, the same as we had a few for non-travel based communication, like beacon fires or semaphore. None of this past-history speaks to our future
survival buts it’s a reminder that a belief our world will end and we have nowhere to flee to doesn’t mean civilization falls into ruinous despair awaiting the inevitable end, whether that is from divine wrath or a fiery consumption by our Sun or a frigid dissolution a trillion-trillion years from now in a dark and entropic Universe. One day our sun will end, and with it all the days and nights of Earth, and indeed even most of the tricks we have discussed on this show for extending that like starlifting and refueling rely on technologies that make interstellar travel a piece of cake. We estimate in a billion or so years, maybe half that, maybe double, the Sun will have brightened enough to burn off our atmosphere and seas. And we have tricks for preventing that, like shading the planet with orbital shades & mirrors or even moving the planet, but both imply a skill at space travel beyond what we have now. We tend to assume we wouldn’t even make it that long though and that’s a fair point, if the Sun might boil our oceans away in as little as half a billion years from now, well half a billion years ago is when we crawled out of the ocean and we don’t look or act much like we did then. We often assume that this period,
humanity’s rise to master Earth and then this region of space, would be so significant that all life descended from us afterward would view humanity as very important, their most noteworthy ancestors or creators, the form of life which dominated our world then our galaxy and perhaps beyond, or at least made the first big steps out there, as Neil Armstrong so eloquently put it. For a civilization looking back from the edge of the end, one where we always dwelt on Earth, life would have arisen in the seas billions of years ago and those seas slowly disappeared with various species and civilizations arising and falling and humanity probably just one of them. In another billion years, if humanity wiped itself out and it took 10 million years for the world to heal enough and some other critter evolve enough to replace us and do it again, then we’d just be one of a hundred great civilization making species. And realistically it would be
much shorter intervals. Probably more like tens of thousands of years and tens of thousands of iterations. As we saw in the Silurian Hypothesis, it isn’t likely we would be forgotten, we would still have our wikipedia page, possibly literally, but we would probably not be noted as the grandest or greatest or even necessarily the first. Let’s consider some scenarios though. First, I can’t really accept that science and technology don’t allow space travel, so while we will discuss that scenario too, let’s start by hypothesizing that we can not get off Earth because we are told not to. This might be that the programmers of the Matrix give up
on trying to convince us there’s a real universe out there to colonize and just stop bothering to simulate it or maybe very powerful and eternal aliens or divine agencies show up and say “No, this is your one and only world, keep it or wreck but no replacements and no returns.” and we might contemplate if Earth’s orbital space, which we are clearly very active in, should count, perhaps out to the Moon, or even the whole solar system. We might also imagine that it is our own decision. Let's imagine we do start finding signs of life all over the place, exoplanets seemingly teeming with them and even Mars and Europa and Venus and more. Perhaps also that,
as many suggest, ethics and right and wrong are things that can be logical deduced and universal, that humanity will reach that ethical code and other aliens all converge to that and everyone really does say “It is wrong to take other worlds, even from an Amoeba, even from where an amoeba might be likely to one day appear.” Or perhaps we come to fear what colonies will turn into once away from us, and us powerless to stop it. Space travel is possible but we forbid it and shoot down any ship seeking to leave, so that their distant descendants don’t in turn surround us with possible enemies. After all, we talk of how space will benefit humanity but the reality is that’s only true if we pick a broad definition for it. Realistically a future of space colonization in a no-FTL universe is one where humans spread to the stars and mutate and genetically engineer and cyborg themselves up till in even a few thousands years they act, look, and think little like we do now. On our lone world we probably still have
all the science we need to discover how to become post-scarcity, living vastly extended lifetimes in prosperity with robots doing the grunt work and us free to pursue higher aspirations. We can still make a world of many layers and arcologies, still have a trillion virtual realms for us to explore, weirder than nature will produce and not requiring centuries of expensive travel to reach. We can still live extended and augmented lives. Here on Earth Alone we can still rise to Olympian Heights. Claiming more worlds on which new research and development and experiments with civilization can occur may help speed that up, but there is danger there too. Some may say it is better to have this one world, surrounded only by silence, then to have a future where we still have only this one world, but are surrounded on every side by our mutant offspring and vulnerable to whatever abominations of technology some reckless or ambitious colony might unleash upon us and their neighbors. There is a good deal of sense to that,
mathematically. An AI which takes over a planet as a single megamind has to think twice about expanding that domain since their own mind can stretch only so far from light lag restraints and their progeny may be as deadly to it as it was to us, and surely more so statistically than empty space would be. Is it any different of an equation for us, truly? We might imagine a future where any ship on a trajectory past the Moon is destroyed by great sky fortresses looming over our world, and this is a future where we can hold back the Sun with solar shades all the way to the final sunrise they are burned away and our world with them, 4 or 5 billion years hence. Or we might imagine that even satellites are forbidden,
and that instead huge towers permit communication between themselves as nodes like in the pre-space days. For communication, this would be no great limitation, as we might cocoon our planet with fiber optic cables to allow far denser and faster communication than our satellite grid allows. We talk of solar shades in orbit but perhaps instead we might make high-stratospheric balloons, reflective on one side to sunlight or those frequencies of it we value less. Indeed we might decide the best approach would be to dome our whole world over, a worldhouse as we call it, and permit no air to leak and to reflect away any light we didn’t want before it was absorbed by land or sea or air as heat. Indeed we might build radiating trunklines and masts on these to let us move heat from hot to cold areas or remove it from the world by radiating it into the vacuum. Done correctly, and without ever needing spaceships, we could slowly push Earth from the Sun by means of reflected light or superheated helium or other gases vented toward the Sun at ion drive speeds. Earth would lose mass, like any rocket, but it has so much and the sun
provides so much power to drive that process. Indeed it is worth remembering that once you remove all the material in the Sun and the Gas Giants, hard to reach and use, Earth makes up much of the remainder. Indeed Earth outmasses all the rocky planets combined, and very nearly ever rocky planet, moon, and asteroid combined, with the majority of the remainder being in Venus. So it isn’t that our solar system’s mineral resources are really necessary to keep Earth going. Nor do we need hydrogen or deuterium or helium-3 from other worlds to run our hypothetical fusion plants, though I can’t imagine how we could have those and not be able to do space travel with them. We mostly only want all those rocks in space for new places for humanity and to help fuel that expansion. Gold and platinum from
asteroids sure would be nice for encouraging and assisting early space expansion but every asteroid combined doesn’t have as much gold and other precious metals as Earth’s own crust, which is roughly ten times the mass of the entire asteroid belt, while still being less than a percent of Earth’s total mass. We’ve discovered around a quarter of a million tons of gold to date, but that is only around a millionth of what’s in the crust alone and the same is true of basically everything we mine, albeit not in dense and easily reached ore veins. As long as you have energy, you have the ability to keep refining and recycling and centrifuging those minerals, and on geological timelines they do shift around with the mantle. In truth as long as the sun keeps shining we should be able to support our current population and more, but even if we did need to go back to a lower population density, say a billion people, to be a stable ecology while still having plenty of room for crops, livestock, biofuels, solar, wind, geo, and hydropower, that remains a very impressive civilization. We believe perhaps 100 billion people have lived thus far, with around half in the last two thousand years but the other half spread over far longer. Most since we learned farming and agriculture, but more humans lived before we had agriculture than live now. Maybe not by much
though, even over hundreds of thousands of years. It varies a lot on vague estimates of prehistoric populations and where you draw the line on what’s human, but the most recent calculation I saw was 117 Billion, currently growing by about 82 million a year, with 34 million dying each year, and us set to hit 8 billion humans alive shortly after this episode comes out. For simplicity of numbers though we might assume a steady population of around a billion, each person living a century, for a billion births and deaths each century and in a billion years that would mean 10 million centuries or ten million-billion people, or 10 quadrillion, or a million times our present population or a hundred thousand times as many people as have ever lived.
Rough numbers and for my part I think we could support a lot more folks than that. So consider this, ours is not a great civilization but rather the most recent and mighty collection of many civilizations who are heirs to thousands of great cultures who are spread over thousands of years, and mostly unknown to us. Few empires numbered a billion souls over their entirety, and most folks lived in realms and times far less grandiose. Millions of those could rise and fall and overlap each other in time and space before ever the Sun finally set on Earth. That is not a future to be depressed about or sad for, anymore than a person should lament having a million dollars because someone suggested they might make billions and a million is all that materialized.
Nor is our longevity or sheer numbers the measure of our worth. Many a person has striven for immortality in the form of being remembered by statues and histories, and if that is a good way to persist, then to have our history recorded for a few billions of years before being burned up is also nothing to be sad about, simply because it falls short of the trillions of years or even longer that we often contemplate on the show. And as I’ve mentioned before, digital data and cheap data storage plus the internet mean that unlike virtually everyone who lived before, you have good odds of being remembered until this world is no more. But I don’t think the measure of man is only in how tall his statue is or how long his tale is kept, and the same for all mankind. Our forgotten and unrecorded civilizations are our loss, not theirs, we are made less by not knowing them, and while it would be a great shame if a fire burned every copy of Shakespeare or Tennyson or Mozart or Bach, it doesn’t make their works any less grand, it just makes the world that follows poorer. And if the sun burns up our whole world, and everything we were with it, then it is no loss to us today, merely to those on that day and on all the tomorrows that follow somewhere on some other world we never got to see.
If we stay here, it doesn’t mean we are vulnerable to having all our eggs in one basket. There’s really only a few improbable scenarios that would sterilize our world, even on billion year timelines, and being planetbound doesn’t mean you are defenseless against those scenarios. Great big orbital space guns or missile platforms work wonders. As we looked at in our episodes
Asteroid Defense and our Collab with Joe Scott on 5 Doomsday Scenarios and how to prevent them, with a bit of forewarning and detection there’s very few ways a natural calamity can endanger us that can’t be managed and survived. Man-based cataclysms alternatively, ones able to threaten whole worlds, can also threaten whole interstellar empires, and have more place to originate from in one. The hyper-intelligent self-replicating swarm that devoured your whole world and which you cannot resist probably is still irresistible when it gets to your other colonies, or if it came from one of them. Indeed if it is a choice,
like we considered in our episode years back on Stay-At-Home civilizations who could expand into the galaxy but choose not to, then their technology renders them safe from natural disaster even if bound to one world. And when it comes to technological threats, the nightmares we might spawn, a billion worlds might spawn them a billion times faster, and far harder to detect and kill in weaker embryonic states then some homogenizing swarm or von Neumann berserker probes might be once they got rolling on some lightly settled colony planet far from oversight and control. Alternatively many would say the nightmare we might spawn is us, and that any world we go to will suffer the same fate as ours. But if that is so then colonizing worlds really
offers no escape from that and what’s more, colonizing a planet is always going to be harder than repairing one you already had but damaged. The technologies and wisdom humanity needs to spread to the stars is the same that permits us to keep our world the wonder that it is. If we don’t get that then it doesn’t matter if we’re stuck on this planet or not, we would carry our doom with us whether we stayed or went, and not for far or long either way. This to me though is the greatest loss. If you see humanity as a plague, replicating itself over a galaxy that will descend into eternal war among its greedy divergent spawn, then all the better if we are stuck on this world until our Sun burns it up and us with it. But if
you see us instead as gardeners and sculptors, and the galaxy beyond as our garden and quarry, then even if we were swept away by some descendant or creation of ours, then we still are victorious in seeding that garden, even if in the end we are only the seed. That’s what truly happens if we can’t ever leave Earth. It isn’t the end of humanity or a doorway to despair, merely a door to heavenly heights we must pass on, while still having so many more great paths available to us even here, on our one lonely world, our pale blue dot. So yesterday I was at the store in the check out line with my wife when my phone lights up with a call from my bank. They never call me and it was after hours so I was immediately worried they were about to tell me my identity was stolen or were calling to tell me they just successfully wired all my funds to my new bank on non-extradition island. I’m half deaf from my time in the military and pretty much always use my speakerphone but I didn’t want to put that call on speakerphone so I had to ask them to wait while I got outside. Thankfully it turned out they were
just calling to wish me a happy birthday and I could catch my breath again. Then kick myself, because I’ve got a very nice pair of Raycon Everyday Earbuds with noise isolation, which have this very pocket-friendly carrying case and charger that makes it easy to carry them around everywhere and everyday, but I’d left them at home. Earbuds are just plain handy for leaving you both hands free and for letting you hear things around loud or changing noise levels, and Raycon’s noise isolation is superb, I’ve used it for listening to audiobooks while mowing or running drills and saws, or taking a conference call while going for a bike ride, and Rayon Earbuds let you reject calls or navigate audio tracks just with their earbuds, leaving your hands-free. Raycon’s Everyday Earbuds have optimized gel tips for the perfect in-ear fit, so they are comfortable and they will not budge or fall out. They’re water resistant, I’ve washed my on accident before, and they give you high quality audio at half the price of other premium audio brands. That’s
probably while Raycon Everyday Earbuds have tens of thousands of 5-star reviews, including mine. They’re just all around great earbuds in terms of quality, versatility, comfort, and cost. The individual earbuds have a 8 hour playtime battery life and they recharge in their compact carrying case, for 32 hours of listening time without needing to plug into a wall, plus a wireless charging feature for the case you can try out. Raycon Everyday Earbuds are Siri and Alexa compatible, and have both noise isolation immersion mode and awareness mode for when you need to hear the noise around you, plus three sound profiles, pure sound, for podcasts and audiobooks, a bass-boosted mode for music with a lot of beat, and balanced mode. So if you’re looking for a great and affordable listening experience and want to help support our show while you’re at it, just click the link in the description box or go to buyraycon.com/isaacarthur to get 15% off your Raycon purchase!
So today we asked what happens if we have to remain on Earth and this weekend for our Scifi Sunday episode we’ll go the other direction and ask what Alien Environments might be like. Then next week we’ll go even farther and ask if space travel might become so mundane you could have Your Own Personal Spaceship, which we’ll look at on October 20th. Then we’ll ask what would happen if you damaged that spaceship on October 27th, and then close out the month on Halloween weekend with our Livestream Q&A, on Sunday, October 30th, at 4 pm Eastern Time. Join us live to get your questions into the chat so they can be answered. After that we’ll head into November to discuss refueling the Sun,
an option that could make it possible for us to keep Earth going for trillions of years to come. If you want alerts when those and other episodes come out, don’t forget to subscribe to the channel and hit the notifications bell. And if you enjoyed today’s episode, and would like to help support future episodes, please visit our website, Isaac Arthur.net, for ways to donate, or become a show patron over at Patreon. Those and other options, like our awesome social media forums for discussing futuristic concepts, can be found in the links in the description. Until next time, thanks for watching, and have a great week!